How to Prepare an HCl Solution with pH 4.2 from pH 2.9?

[Jeanclaud]

Homework Statement

Knowing that HCl is strong acid we want to prepare HCl solution of pH=4.2.starting from a solution of pH=2.9.Explain briefly the procedure that should be followed to do this operation.

Homework Equations

pH=-log(H3O+)
3. The Attempt at a Solution [/B]
I calculated: At beginningC(H3O+)=1.258×10^-3mol/L
at end C(H3O+)= 6.309×10^-5mol/L
and please I want to know is the procedure dillution?

 

[Borek]

Yes, it is dilution. You need to find out in what ratio to mix your original acid with water.